python2.pkgs.pycairo: fix cross

pkgs/development/python-modules/pycairo/1.18.nix

···
   ];
 
   mesonFlags = [
-    "-Dpython=${python.interpreter}"
+    # This is only used for figuring out what version of Python is in
+    # use, and related stuff like figuring out what the install prefix
+    # should be, but it does need to be able to execute Python code.
+    "-Dpython=${python.pythonForBuild.interpreter}"
   ];
 
   meta = with lib; {

pkgs/top-level/python2-packages.nix

···
   pyblosxom = callPackage ../development/python-modules/pyblosxom { };
 
   pycairo = callPackage ../development/python-modules/pycairo/1.18.nix {
-    inherit (pkgs) meson;
+    inherit (pkgs.buildPackages) meson;
   };
 
   pycangjie = disabled pycangjie;